Cell Structure
& Function
The Cell
•A cell is the smallest unit that
is capable of performing life
functions.
Amoeba
Proteus
Bacteria
Nerve
Cell
Plant
Stem
Red
Blood
Cell
Microscopes and Cells
• 1600’s.
–Anton van
Leeuwenhoek
first described
living cells as
seen through a
simple
microscope.
Microscopes and Cells
–Robert Hooke first used a
compound microscope to
view thinly sliced cork cells.
•Compound scopes use
a series of lenses to
magnify in steps.
•Hooke was the first to
use the term “cell”.
Microscopes and Cells
• 1830’s.
–Mathias Schleiden identified
the first plant cells and
concluded that all plants
are made of cells.
- Thomas Schwann made
the same conclusion about
animal cells.
Cell Theory
1. All living things are made up of 1
or more cells.
2. Cells are the smallest working
units of all living things.
3. All cells come from pre-existing
cells through cell division.
Number of Cells
Organisms may be:
• Unicellularcomposed of 1 cell
OR
• Multicellularmade of many cells
Cells can be Eukaryotic or
Prokaryotic
•Prokaryotes :do not have a nucleus or
organelles (bacteria).
•Eukaryotes: have a nucleus and
organelles (plants, fungi, animals,
protists)
Organelles
• Cell structures that have a specific
function and are surrounded by a
membrane that are found in eukaryotes
only.
Prokaryotic vs. Eukaryotic
Http://micro.magnet.fsu.edu/cells.html
Prokaryotic Cells
• Believed to be the
first cells to evolve.
• Lack a membrane
bound nucleus and
organelles.
• Genetic material is
free in the cytoplasm
• Ribosomes are only
other cell structure.
Eukaryotic
• 2 major types of eukaryotic cellsPlant and Animal cells
Plant
http://library.thinkquest.org/C004535/eukaryotic_cells.html
Animal
Cell Structures
& Functions
Cell Wall
• Found outside of the
cell membrane in
plant cells & bacteria
only
• Contains cellulose
that provides support
(rigidity) & protection
Cell or Plasma Membrane
• Outer membrane of
cells that controls
movement of
substances in and out of
the cell
• Double layer (bi-layer)
• In plants and bacteria,
this is within the cell
wall.
Cytoplasm
• Gel-like mixture inside cells
• Surrounded by cell membrane
• Contains cell structure that carry out
specific jobs ex. Mitochondrion, nucleus
• Provides a medium for chemical reactions
to take place
Nucleoid
• In prokaryotes.
• Region of the
cytoplasm where
chromosomal DNA is
located.
• Singular, circular
chromosome.
• Smaller circles of
DNA called plasmids
are also located in
cytoplasm.
Ribosomes
• Each cell contains
thousands
• Make proteins
• Found on
endoplasmic
reticulum & floating
throughout the cell
cytoplasm
Organelles
Nucleus
• “Control center”
• Directs cell activities
• Contains the genetic
material (DNA)
• Separated from
cytoplasm by nuclear
membrane (or nuclear
envelope).
Nuclear Membrane
• Surrounds nucleus,
separates DNA from
cytoplasm
• Made of two layers
• Openings called
pores allow some
materials to enter and
leave nucleus
Chromatin
• In nucleus
• Genetic material
(DNA) of cell in its
non-dividing state.
• Ie. Uncoiled
chromosomes
• Contain instructions
for traits &
characteristics
Nucleolus
• Dark-staining
structure in the
nucleus
• Makes ribosomes
that make proteins
Rough Endoplasmic Reticulum
• Network of continuous
sacs, studded with
ribosomes.
• Internal delivery
system of the cell.
• Manufactures, processes, and transports
proteins for export
from cell.
• Continuous with
nuclear envelope.
Smooth Endoplasmic Reticulum
• Similar in
appearance to
rough ER, but
without the
ribosomes.
• Produces lipids, involved in
carbohydrate metabolism, and
detoxification of drugs and poisons.
Golgi Apparatus
• Protein 'packaging plant‘
• Modifies proteins and
lipids made by the ER
and prepares them for
export from the cell.
• Encloses digestive
enyzymes into
membranes to form
lysosomes (transport
pods).
Lysosome
• Digestive 'plant' for
proteins, fats, and
carbohydrates
• Digestive enzymes
break down cellular
waste and debris
• Transports undigested
material to cell
membrane for removal
• Cell breaks down if
lysosome explodes
Mitochondria
• Cell “powerhouse”
• Membrane bound
organelles that are
the site of cellular
respiration (use
glucose to produce
cell energy, ATP)
• Active cells like
muscles have more
mitochondria
Animal Vacuole
• Membrane-bound
sacs for storage,
digestion, and waste
removal
• Contains water
solution
Plant Vacuole
• Plants have large
central vacuoles that
store water and
nutrients needed by
the cell.
• Help support the
shape of the cell.
Chloroplast
• Usually found in plant
cells
• Contains green
pigment chlorophyll
• Where
photosynthesis takes
place
• Produces plant food
(sugars) and oxygen
gas
Cilia and Flagella
Cilia
Flagella
• External
appendages from
the cell membrane
that aid in
locomotion
(movement) of the
cell.
• Cilia also help to
move substance
past the membrane.
Centrioles
• Found only in animal
cells.
• Self-replicating
• Made of bundles of
microtubules.
• Help in organizing cell
division.
Cytoskeleton
• The cell’s skeleton
• Made of
microtubules and
filaments
• Give the cell
shape, strength
and ability to move